Miller is a waste of time IMO, especially since the forest service removed "the squeeze". Sherman even has more rocks than Miller. Miller is just a super dusty fire road with one optional obstacle before you get to the top. And after the fires a few years ago, the scenery really sucks too. At least Sherman is scenic, has great creek fishing in the area, and the weather will be much cooler. I honestly think that freeway ridge is better than both of those trails from a technical standpoint, even with gatekeeper destroyed. If Freeway is getting boring for you, run it with Josh/Roger/ or me and we will show you some of the optional stuff.
Nightmare Gulch / Last Chance Canyon is very scenic, but also are very easy trails. I like to explore old mines and historical places, so I still love this area even though it gets 100000 degrees in the summer.
I think that BC109 is a great day run, and halfway point for the Bako and Oxnard clans to meet. It sure is better/more scenic than the other local trails and definitely has more technical options than the others. But realistically, from Bako, 1/2 hour more of driving will have you at Calico.
If looking for a little more than a day run and a good area to escape the heat, the Shaver Lake area trails are hard to beat.
Be mindful that 90% of the trails out there are easy if you bypass all of the optional obstacles - even the Rubicon in some years is like that. The problem with Miller is that it lacks bonus obstacles, for the exception of 1 rocky outcropping as you approach the top. So its not really what trails you run, its who you follow!!
MFDD out!